Tenth-century Normandy is a world fraught with dangers for the historian. The Vikings who founded Normandy were illiterate, and left no account of their own. What information we do have comes from the neighbouring Franks, who distrusted, and in many cases hated the invaders from the north and left strongly biased accounts that tended to view the Vikings in Frankish terms. Furthermore, the Viking settlement at Rouen falls, annoyingly, during precisely a period when no major Frankish historians were active; several thorough German annals end around 900, and Flodoard of Reims, our best source for the early years of Normandy, only begins in 919. And during the tenth century, there are several periods of years or decades where nothing that occurred in Normandy was of interest to the Frankish writers, and so we know precious little of those times. As a result, since the information is so scanty, the danger is great for historians to read things into early Norman history that might not actually be there.
There are two issues that colour the views of every Norman historian. The first of these is Dudo of Saint-Quentin, a Frankish writer of the early eleventh century who purported to write a History of the Normans under the first three rulers, from the beginning until 996. For a long time, historians have discounted Dudo’s work in fairly strong terms, recognising that much of what he says is inherently implausible and that his book was strongly coloured by the way he wished to portray the Normans of his own day. But it is very difficult to reject Dudo, since the vast majority of the information we have on tenth-century Normandy comes from him, and indeed, even those historians who reject him tend to tell a story influenced by him in at least the broad outline. Recently, some historians have begun to appreciate Dudo not as an historian of the modern sort, but in his own context, as a Carolingian-educated writer of the eleventh century trying to make points about the contemporary situation, and thus a good source for eleventh-century Norman history, even if not for tenth-century events. And a school of thought is developing in France that is trying to ‘reform’ Dudo’s reputation, and give much greater credence to his history. However, Dudo should only be used with the very greatest caution, when there are very strong reasons to believe his version of a particular event. For the most part, this will be early Normandy without Dudo.
The second issue is the contested nature of the history of early Normandy. The dispute is best seen in the works of the two leading English-language Norman historians of recent years, David Bates and Eleanor Searle. To Bates, the Vikings of Rouen very quickly assimilated into Frankish culture and political structures, so that within a generation or so Normandy was in effect a territorial principality on the Frankish model, and tightly integrated into the Frankish world. Searle, on the other hand, saw the Vikings of Rouen as Vikings first and foremost, who maintained their cultural distinctness throughout the tenth century and indeed well into the eleventh, only fully adopting Frankish ways, and then only imperfectly during the reign of William the Conqueror (1035-1087). Searle is generally more convincing on the tenth century (and to be fair, Bates devotes only a few pages of his book to that period), and Bates for the eleventh, but there is room for compromise. Some Vikings assimilated more quickly than others, and some Frankish ways were adopted more quickly than others. But while I see the early Norman rulers as being, in effect, ahead of the assimilation curve, I still do not view Rollo (c.911-c.930) or William Longsword (c.930-942) as primarily Frankish royal officials; they were still in many ways Vikings, and even Richard I (942-996) had his Viking side.
The words used to describe people strongly colour our perceptions of them, and nowhere are the dangers of this greater than in tenth-century Normandy. It is, for example, customary to speak of Normans and Vikings, and thus draw a sharp linguistic boundary between them. Yet ‘Norman’ (Latin: Northmannus) is simply the medieval Latin word for Viking; Frankish writers speak of ‘Northmanni’ not only in what became Normandy, but also elsewhere in the Frankish realms and in Scandinavia as well. To the Franks, there was no distinction between the inhabitants of Rouen on the one hand, and the Vikings in the long-boats who sailed from Norway to pillage the Frankish countryside; they were all equally ‘Northmanni’ (or, in the somewhat harsher word of Richer of Reims, a late-tenth-century historian, they were all equally ‘pirates,’ even after the ‘Northmanni’ had been settled at Rouen for a century and were becoming an accepted part of the Frankish political landscape). Thus, to write of Normans and Vikings is to create an artificial distinction that would not have been recognised by contemporaries, and instead I will always use ‘Northmen.’ Likewise, the word ‘Normandy’ has very strict connotations for historians. It is the territory associated with the 11th and 12th century duchy, extending from Eu in the east to Mont-Saint-Michel in the west, with a clearly-defined southern frontier. But in the tenth century, Normandy (Latin: Northmannia) means Viking-land, or Northmanland. As late as the 1030s, Adémar of Chabannes, a clerical writer in Aquitaine, used Northmannia equally to refer to the future Normandy, other Northman settlements in the Frankish realm, and the Northmannic homelands of Denmark and Norway. Northmannia was simply a place where Northmen lived, and was not in any way associated exclusively with what we consider Normandy (in fact, the one time Adémar uses Northmannia to mean Normandy is also the one time he feels the need to explain what he means -- ‘In that Northmannia that previously was known as Neustria’). During the tenth century, the territory that would eventually become Normandy was never united under the control of any one man or dynasty, and it would be the task of the eleventh century to establish finally those boundaries.
Furthermore, William the Conqueror’s ancestors are often referred to as the dukes of Normandy, or more recently the counts of Rouen. But they are known to have held neither of these titles during the first decades of their existence. The only term used regularly to describe them in contemporary writings is princeps, or prince. But we have to call them and their lands something, so I will refer to Rollo and his immediate descendants as the Rollonids; for the tenth century I will call the land where the Northmen lived Northmanland, and the territory ruled by the Rollonids will be called the Rollonid Principality.
 For Flodoard of Reims see, Les Annales de Flodoard, ed. Philippe Lauer, Collection des textes pour servir à l’étude et à l’enseignement de l’histoire 39, Paris: Picard, 1905 and Historia Remensis ecclesiae, ed. Martina Stratmann, Monumenta Germaniae Historica, Scriptores 36, Hannover: Impensis Bibliopolii Hahniani, 1998. These are discussed at great length in Michel Sot, Un historien et son Église au Xe siècle: Flodoard de Reims, Paris: Fayard, 1993.
 An important source for this period is Richer of Reims and is available in two editions: Histoire de France, edited by Robert Latouche, Les classiques de l’histoire de France au Moyen Age, 12, two volumes, Paris: Champion, 1930-37 and Historiae, edited by Hartmut Hoffmann, Monumenta Germaniae Historica, Scriptores 38, Hannover: Impensis Bibliopolii Hahniani, 2000. Richer’s career is discussed in Jason Glenn, ‘Political History: The Work of Richer of Saint-Remigius,’ Ph.D. dissertation (University of California, Berkeley, 1997).
 The most substantial source for early Norman history, though deeply flawed, is edited in Dudo of Saint-Quentin, De moribus et actis primorum Normanniæ ducum, ed. Jules Lair, Mémoires de la Société des Antiquaires de Normandie 23, Caen: F. Le Blan-Hardel, 1865, and translated in Dudo of Saint-Quentin, History of the Normans, trans. Eric Christiansen, Woodbridge: Boydell, 1998. A much-needed new edition (with translation into French) is in the works from Pierre Bouet. A transcription of one manuscript with translation into English can conveniently be found at Dudo of St. Quentin’s Gesta Normannorum, edited and translated Felice Lifshitz. Important discussions of Dudo’s usefulness as a historical source can be found in Henry Howorth, ‘A Criticism of the Life of Rollo as Told by Dudo of St Quentin,’ Archaeologia 45 (1880): pages 235–50 (old and often ignored, but remains fundamental); and Henri Prentout, Étude critique sur Dudon de Saint-Quentin et son histoire des premiers ducs normands, Paris: Picard, 1916 (extremely thorough and dripping with disgust at its subject). Recent accounts that see Dudo not as a failed historian but rather as a successful writer in his own, eleventh-century context, include Eleanor Searle, ‘Fact and Pattern in Heroic History: Dudo of Saint-Quentin,’ Viator 15 (1984): pages 119–37; Victoria B. Jordan, ‘The Role of Kingship in Tenth-Century Normandy: Hagiography of Dudo of Saint-Quentin,’ Haskins Society Journal 3 (1991): pages 53–62; Felice Lifshitz, ‘Dudo’s Historical Narrative and the Norman Succession of 996,’ Journal of Medieval History 20 (1994): pages 101–20; Leah Shopkow, ‘The Carolingian World of Dudo of Saint-Quentin,’ Journal of Medieval History 15 (1989): pages 19–37; Leah Shopkow, History and Community: Norman Historical Writing in the Eleventh and Twelfth Centuries (Washington D.C.: Catholic University of America Press, 1997); and Emily Albu (Hanawalt), ‘Dudo of Saint-Quentin: The Heroic Past Imagined,’ Haskins Society Journal 6 (1994): pages 111–18.
Very few Norman sources for the tenth century exist. A lament for William Longsword has been printed twice, in Philippe Lauer, Le règne de Louis IV, Bibliothèque de l’École des hautes études 127, Paris: Émile Bouillon, 1900, pages 319–323; and in Phillipp August Becker, ‘Der planctus auf den Normannenherzog Wilhelm Langschwert (942),’ Zeitschrift für französische Sprache und Literatur 63 (1939): pages 190–197. And four or five charters of Richard I survive in later copies; Recueil des actes des ducs de Normandie de 911 à 1066, ed. Marie Fauroux, Mémoires de la Société des Antiquaires de Normandie 36, Caen: Caron et Compagnie, 1961, nos. 2–5 and possibly 6, discussed in detail in Robert Helmerichs, ‘Princeps, Comes, Dux Normannorum: Rollonid Designators and Their Significance,’ Haskins Society Journal 9 (2000).
 Elisabeth Deniaux, Claude Lorren, Pierre Bauduin and Thomas Jarry La Normandie avant les Normands de la conquête romaine a l’ arrivée des Viking, Rennes, 2002 sets the context. François Neveux, La Normandie des ducs aux rois (Xe–XIIe siècle), Rennes: Ouest-France, 1998 is a valuable recent study, though to my mind he takes Dudo far too seriously. Henri Prentout, Essai sur les origines et la fondation du duché de Normandie, Paris: Honoré Champion, 1911, though dated, is still of value. For a provocative and important reinterpretation of some aspects of tenth-century Normandy, see Felice Lifshitz, ‘La Normandie carolingienne: Essai sur la continuité, avec utilisation de sources négligées,’ Annales de Normandie 48 (1998): pages 505–24.
 David Bates, Normandy before 1066, London: Longman, 1982, 2nd edition, Oxford: Basil Blackwell, 2003.
 Eleanor Searle, Predatory Kinship and the Creation of Norman Power, 840–1066, Berkeley: University of California Press, 1988.